SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8021045105de06fc583b8692cb629202c03638244e4125460825efa8754446b7' 
  AND token = 'qgmLqlVwih/fD+ZQM1UEtVh3cOn/S+xJQWcRZzONPmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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