SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '159e0748815d1a2e7cefb981409d792d85566298eaf6d353495ab2b7c1d86c01' 
  AND token = 'RP27itoFgNcYrzldxKQ6LDneogn11DxkreP+zXwI43E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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