SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f0371cb87653cab8c22363d5113a9d02f992e55c04a0b151dd4bbcc125aa682' 
  AND token = 'KlOqMbRCPpliqJOsn4UjwZ3gBw0BksihCnoWeM2pQkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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