SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef7fa2f41364202e03192f0f0dfbee8ec420c7dd64f26565ba900301e1e8f749' 
  AND token = 'tr+lnxo5tKPYkXEX16Yj0PzESLcAg6pCqJVG1n1J7sc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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