SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3abb0c57efa054129795a49723ad839f685ce20f6fc5b1557d7d6c504d96ada' 
  AND token = 'wt/9GZR0ZzQq71JGXmzcL/njyhmcPSQQP/2q95mP1Fg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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