SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ef8b24ee0c7993d7bbae7f46d16c1809608685478e432b068db46ae2f10865b' 
  AND token = '938qIpufImaHdWqAAGRqRQ4pixcZnI43W+OxDJeJCrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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