SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '940513a42e2c42e43e8fe2b433536c713090e3f7ff2b9c41fb4daebb92f35fe7' 
  AND token = '0QMSQf2vo3CtIQR7jpiPhbXfi0etmqTqTQW96bpqMbU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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