SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d00b2734bc2fe0a82fb0e2f8b722e959a700b6baf6d41c8064c1604d54f56e8' 
  AND token = 'lR4PQRxAc5Zr7H6aohd9xFxwks7zbNXZWefJ6MvxOYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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