SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a900b11b91a655230744e86ed858451abf9a37ed913fac1fd527baa97af855c4' 
  AND token = 'U8mDvrS9vwVRGHp3wp1dpiFKgD8ZTpedXYumH2xxAfU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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