SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88aff8844c6e9b6e704d1def2c4287e54bb4885651f07fb33da23603131af51c' 
  AND token = 'H3zbwzKpM8/AGTCdELKnmzzZ+sPU6MF/JRMc+jq/rMo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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