SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50fc4d0db483702ca89da137da6296ab3eed3469e237ee5d0a45c55753fcf66b' 
  AND token = 'M1ggS3WnVJPvPkDZPpb67DQzk0BuS3VeWcqGeShlHdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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