SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1f43b891ea3e0d162d2dc7221ea4727908fb6f2bde65fbbdc02099b119e2a7e' 
  AND token = 'KBlSOAVhg1NOwfRtyqf/euDY88XiQR+aZLdvD1/+qDI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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