SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ef0e58b42f2474ed540fb3b7b70057dfb09d6187390789cc0ecccbdfb49f274' 
  AND token = 'iIg6C+IecVChfg96fkELsjUVRBvABgobq6svNgAuDGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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