SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b23363ff21a2d4f3432f8072d35ae44aa66426e1f57d124cf295d2275de5878' 
  AND token = 'v5YpTcnL5vtXfp/qJve/hTLBxOASCh4XrCslcW4agoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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