SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76cb3d14a308c531dbb13a504056e606651c1b4cef7dfebf070d971e333d25d3' 
  AND token = 'RQHtFfwuUcBRmiBTiHPR+fMQ7aH77SmlHjHIuYFIijY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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