SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec0c1993a512641b67a077d32a036bc99ba2880417d2463d84fc036fac67baea' 
  AND token = 'q+GAhQjp+Waw7mj84dTtFrlqGtPSoxqPk0fJnLBwohI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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