SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '06f5c563de0bd4fcc845df5a8da58b5df28172936b271596113b025c9476fee4' 
  AND token = 'qCnekWnfUViH19NfVlQWO6iyRt7QRwfBjtSFWgUhNjc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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