SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4a8b4a8c543ef54f6da85cdafdd1561e62bab69bb5763cb1afb8da27ea6a095' 
  AND token = 'nPSHSaQDgiWNCU/42p8rgAN8psOu72B5xGRLumunM0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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