SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fe0b2d9262c185e22911875f8ad98eaadae98c942677906d924edaf93805539' 
  AND token = 'VK/iK6mVGar0cear/LSN66pcTQAOPi+y95lrPDaxcTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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