SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a2b1623a476c846b7b6b32e3044b2d77b707d525879e30d9792a56f77f38cbf' 
  AND token = 'P4bRASjSVdaslwrQQAV+BmQoIZ9cFmuVJXGLVZ4wmqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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