SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6eaf0b88ad454b7409a68b8a6e98e78f37ce1ae27a27fbd4a498aa9d3df8c498' 
  AND token = '61mtccqkDGeXlL+1eRm7UN0HvUJQ5KRlMSOeNi0xWG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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