SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff50200b62ac9c23b1c63917791e79f7b9003cc7fd08e6fbcf469516f782571f' 
  AND token = 'RlCGG/PJerwHSphECLKK3Qx2dNp0zqjBVQqNDd/t0+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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