SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b5a09a1df7894fd243708577e317c35452c8645d59990fd2754705a658843eb' 
  AND token = 'CbTDaoIHWwtafEtb5kRSGQXrHyQ89c3ajwIswMvPRNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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