SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8bdf753c9043136fbf2964e887d9e5f823049443c411417f6ed580559357e78' 
  AND token = '66Q7aOGb38xFh4GmMzC/Uspz88igr5OaPBobvmw4HAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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