SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9910068c88ad119740ca4e48e80b7894cfdd4c3f6c733135e62f978b49e3c1ba' 
  AND token = 'nRixZF+m/AGdUmGKIGwO3/ueQeRO/IMNrhMF1xgBvjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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