SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ee6cb52afdab0b42616315b692d8510976a36903c87f170da070fe786fbfa20' 
  AND token = 'qdGpIHMOFV0hfrRuEPqnixSTMmdbmZrEUMSbuURu1jk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}