SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba3261471cc63668a9510703aae3c4259cf03123463327b63644ea91b37ad3ba' 
  AND token = 'R+oe+XWAgjuQHsN8xhdctOMVoCqduOLZ5lU2qAH4YlQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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