SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad548b3135adb1c45ac83f802b1789f6b1bf39d3ab32e891042e480228dd9a0e' 
  AND token = '1JADcvxFKb44+eShpl7LmylVJSgCPGrn/aSUW6j6xvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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