SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cda47a4f9cef688170379ef16648329002c20f35624e39c10afbe6ba5439e6c2' 
  AND token = 'OxMwo6ToeGrAOaMbM1mijHVA6VjopyLLmXChGdy40Wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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