SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48b0e6f19bddbdc7f9537524e33526008c50536a9b1aec945e5ecfb3ac34d297' 
  AND token = 'UsGxlVi7GlutohfIRzX2yjq+6vQ0NvqChYtop9TMSEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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