SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1649c365ecd24d253b83927a11e45452ab536d55134c45ca0084c92d78c36bf0' 
  AND token = '6UczmCrvpwWdH+LUQegw/ep09lwcvc4KiujWa2VnXM8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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