SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ff2483a5ec8ce0387278de9a84c4405b3739d26e5a657e059c61e684d0d47c6' 
  AND token = 'AHwUPEtMxcgIyiBHwcCFwr2GiRr5EA+d5QGUtSdzNtQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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