SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50ac22ff721baf05521e1c3ff1894bf8a619ba1dc411d150484673cd23d1cff7' 
  AND token = 'SLpgOT2vBKeyWIvcDcv1HzQwQQ8ct9r8miKMbKXwy8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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