SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91c4d2b0aa705217f1be55ccca4f04cd749212d232075486ca706be8ad05f5f1' 
  AND token = 'sTIwZ2WlyJgv7qjDzgfoUrvXDZugE9VdyrgVWO1VFTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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