SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a4da69fa13b1c86eb3cbce35602cc60d46950ff31b071b29dd95c40a702985c' 
  AND token = '2PAsUmMUSqwGsTONkJliWIHVrycxWXkWw5UvlE3+z+U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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