SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad7acd0778fd7f237117d6acba8d9b940063a0af8b8e014c31490b2c65d25120' 
  AND token = '3rOt+chP8IT/Wwq8hXDvZjpCH+SoqflwJbEOhyJpGFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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