SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9a28771d8354c819aa4628c74154d6e48570fde99bb6150327f2b6740c54f37' 
  AND token = '+/3+HwFXVj5z3NooEqnRLIGZg+PliiB+a24rEW94KuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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