SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9a3448e3b4777f952f8038b2903c49830e093ac939b6442961ee7d94c9500b6' 
  AND token = 'YYzBAWOzpp+YTZpRGRIcz1e6XllZzoG0rwg8uh2ChfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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