SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ccfe740feda6e0eec5dd82df1973308992dba094539ee95018ddd0da79ae18a7' 
  AND token = '0iy01uHShkVmFYgdmEcmSo6qtKeHoUvhg/VpUVxrd50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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