SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45812a4c2fbd40fad470f115b6a804ae3abae283615f59b94701aa1c2dee66c8' 
  AND token = 'onBLZ3/pp5LkDluy2CcITJ1SKA1MSAkTI7411GaTb4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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