SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3fcf136e89e849bef8910d78a3314f7c924997a5207c23a03b5f52055c83d7b' 
  AND token = 'Oih5k/vBvL6TBXiNVcxJqnAzHRX6ZQDTpuyYv6LJWOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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