SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b43f6f9554a689132ee0175de5c2e6bb148ca7bff6cc6365bfdc9779e7064d30' 
  AND token = 'UFek4xWh/kxKVzOl02XwZWAN0v7fErTJFaJjXUGWVaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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