SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21e3a9e999a46ce9cd3b33f3fe2f897a15a0dfe63dd97d4608a914c18f7b8e72' 
  AND token = 'EAUsEytpwMXLZUBKX/7AVzxUlUafoyJ0toDAMaogYQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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