SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '987a03463d4dfadb949e59abcf0577d20abd0dfcea207f4fb0ddd1a7a0daa7d7' 
  AND token = '3tjvcGTySUkriM+DaanmEoVmXrm0/VNrJGe81rKdgRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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