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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8df71b4e4f304d3cf2e743a5b15794b31e89f4b575f8ec69c0c33daa2421f97' 
  AND token = 'PSaIHLKpI8MaCqY97qsSuo572eaAusrYHS/r47kRstk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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