SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3e167529f230edec4524ecce4591ffa0b0fb36c08c4f1b113de0357c65084953' 
  AND token = '6MnvOVI5OgQILst0lV8soh/lZMgV2wXRZObVxQA7GCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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