SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3516294512b13c5a144648d53f88161cd3f0c53f0987835ef03cd19535b0fed4' 
  AND token = 'tTwFscHVV5lWTv9Yb1Tstq86n+MRw2V9dtG7Vyto2vQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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