SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5939f30e39e102331b2ae20e2da48e7517b5dd907c74fbec47f256fb0c95b6b8' 
  AND token = 'YkHKdPETTmymMzXKNlqfjqRzTtYsy38GJDFKUL/HyHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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