SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e577bbf1fb9ec7889ccf48658881b30f79bebbaf951f27937886230915b2fd90' 
  AND token = 'L79u9L4qsWPQB0mqOUu8bOKfFdJppAdzO9ouZL5zpjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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