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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ebdc2f478fafff331236da47dd4912e357eca6ac42bfeeb8790b9909b7a98b4' 
  AND token = 'mQLFuKu/Mbs2/DtoD73KatGk4d2PeALay1MY3TvsiDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}