SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5238523af2d6a1197d2592e0e40079fe76c3ba9de442299fb1072e98b38770bf' 
  AND token = 'mmhRxT4t70VAiXBmE27O2nKC7RflR2UZ/w4zL7oGUP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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