SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4b83a6c350c8b58b8f7c0dc596c3251bb954b6882e0f936b0ff2e33f34e76a5' 
  AND token = 'dKOblcFoaRH+kMW4ueikrB3u7vMzRL+JzfGU8UfRa3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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