SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ed96878ca4649c1ec79a5e5b937630ff45ebcb12b25064bf0fe4ee7ea28a66b' 
  AND token = 'Go9f/JDPqLp4w7AFZH0AByxZ9GNe7LLWceL2mWvyANI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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