SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '790af8395aca477f02c691493cee17311298c4be48cf44d90ba34be62c6eb24e' 
  AND token = 'mtyiN2zfcKZwzHeK65BVdwnNLeZ5SbYIe7H+Eo89TVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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