SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27d20d5b63bcddd6ca4b1b041ab5caeb943a0ce793c7f83e61e3140b5c03637f' 
  AND token = '45bAkfuEiI1ptQeIWXlSCH5pDAFoZvhMxU8RRuGbFp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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