SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '258da934d370c83dc758b633c36c9d5f20930722d8ce96321da7ad8e54fa632e' 
  AND token = 'dwMMXcYkUVRxEqyMK/G+YxPnkRXrBYGvjnpz+oYQ54o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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