SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29f17219696175589cf3b6086c80ca64d633c709e043a68ca3fd7eaf894a6a39' 
  AND token = '5MIur2pSUGOwSCDKKiOcRYCnl7NzIkZtyejbaqrgiGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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