SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '738837ba32d6a5dbd027aaf54ed9ba5f25d635e371e137062b61021f964eb227' 
  AND token = 'EU8FMmZQ1GuBDwVSvqcLcWOYdDPVPjxCgePV01atAEI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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