SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '951c97e1d577eff31639c2be460c105ea474c61f589eaf1cbda68a882761542c' 
  AND token = 'qYFzyF6ljF7XvH0KSMQr4U8KWBxLfSujCJ7kUkm4+Ak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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