SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5ec1516e6cf53312b0806c081f8eea747a722f1491a733b460f8f38dac87815' 
  AND token = 'jYY9sdMMybCzpYj7dhCN+QfRyd4gxqRMWQsOTphrUVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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