SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '404705c58869a100413bc4335a01e4d9e9340a58cd486cfc22cfd77eeb9fc7a4' 
  AND token = 'XSBUkOwIat+kWEgtVBUjF5Qo/5SSdpTQNz3AmK/xQkA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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