SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5265da250fe5018d692e993ff16848185634660e378386c237580b2aad4b649' 
  AND token = 'jnSjpzyCcGRyFhiAcjWxdRzFXG/DNutlyaIT+C5clZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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