SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c1c9ed5597555cb400b501aad9de20d4a6f2d143f56fb44c7d3b0fd331eb1d5' 
  AND token = 'F/daJZO4i9CWD+Xl6JqtUYo+0wyqgv8n+yPzHK+0SMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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