SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f2bfee990dc4e971f54afc8fc0f08f9146884da623d847d9387364e96a8e984' 
  AND token = 'KBF9xXAOLnMHOLzi66b8ID4bTBFOSTtz2jlufgRtE3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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