SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e67c5d857638dfcf562181fbfd79bef222daf35f92856f3886934ddb6e243f0' 
  AND token = '0s9WxpYpungVfeUvTe/FG+hGwqtJnBpUXurR8H4gamg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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