SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '629672eb329bf34c1defb9ba9849e1bdb42caaae48204a1de603ca18148cc584' 
  AND token = 'QG6kyb12Ro5a1lsp03IRbFvltSNmmAvr8OcTUqxqkXU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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