SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6da747ede245633e4df62af01219ade7a031095a258e8051ff6b5bb471878157' 
  AND token = '3MfRTNG3W5n0+Glgeb3iXm7umwWlQd5ImSmbdzwPdSM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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