SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28c0c60401d3fb08702c1c6b018c6ca9cf592bfad99964d13bc987940378f25d' 
  AND token = 'cvhR71G/IzqFY/y+1OTOgVdCYCxyHxSLpo8LuRqpzRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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