SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2984e8613abe02b8c7173300292449e8187110994d58f395a5387d4fcab949c' 
  AND token = '3iJjzvUuAvXQRLK1NqFfD+bHEhPu+Y2gu2dqVJterWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00065

JSON explain

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