SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '866991547e81d3612204f25ce53ff111696d994c270f1db324146aa83dfff953' 
  AND token = '7Hpb5VsbY1/dFNZa/0OOZccbOOcXN1hMnBF/mxf73p8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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